如何從 Firebase 數據庫中的 autoID 獲取值 - Swift

Question

我有這個代碼，我想顯示來自 Firebase 數據庫的 AutoIds 值的計數。 '

    let uid = Auth.auth().currentUser?.uid
    let ref = Database.database().reference().child("userInfo").child(uid!)
    ref.child("users").child(//here should be an auto Id from firebase).observe(DataEventType.value) { snapshot in
        let numberOfusers = snapshot.childrenCount
        print(snapshot.childrenCount)

    }

{ 
  "userInfo" : { 
    "baxUvpqL4cMf9p6mqv9czB0FrNN2" : { 
      "dateOfEvent" : "31.10.2021", 
      "guests" : { 
        "-MRK4bbtD4yL4EIsvMnF" : { 
          "age" : "child", 
          "attending" : "attending" 
        }
      }
      ...

Т這里會有更多的自動 ID，所以我需要它我需要計算所有具有“參加”值的自動 ID。

Answer 1

獲取標記為出席的客人人數的最簡單方法是使用查詢：

let ref = Database.database().reference().child("userInfo").child(uid!)
let query = ref.child("guests").queryOrdered(byChild: "attending").queryEqual(toValue: "attending")
query.observe(.value) { snapshot in
    let numberOfusers = snapshot.childrenCount
    print(snapshot.childrenCount)
}